Network multimedia applications constitute a large part of Internet traffic and guaranteed delivery of such traffic is a challenge because of their sensitivity to delay, packet loss and higher bandwidth requirement. The need for guaranteed traffic delivery is exacerbated by the increasing delay experienced by traffic propagating through more than one QoS domain. Hence, there is a need for a flexible and a scalable QoS manager that handles and manages the needs of traffic flows throughout multiple IPv6 domains. The IPv6 QoS manager, presented in this paper, uses a combination of the packets’ flow ID and the source address (Domain Global Identifier (DGI)), to process and reserve resources inside an IPv6 domain. To ensure inter-domain QoS management, the QoS domain manager should also communicate with other QoS domains’ managers to ensure that traffic flows are guaranteed delivery. In this scheme, the IPv6 QoS manager handles QoS requests by either processing them locally if the intended destination is located locally or forwards the request to the neighboring domain’s QoS manager. End-to-end QoS is achieved with an integrated admission and management unit. The feasibility of the proposed QoS management scheme is illustrated for both intra- and inter-domain QoS management. The scalability of the QoS management scheme for inter-domain scenarios is illustrated with simulations for traffic flows propagating through two and three domains. Excellent average end-to-end delay results have been achieved when traffic flow propagates through more than one domain. Simulations show that packets belonging to non-conformant flows experience increased delay, and such packets are degraded to lower priority if they exceed their negotiated traffic flow rates. Many pricing schemes have been proposed for QoS-enabled networks. However, integrated pricing and admission control has not been studied in detail. A dynamic pricing model is integrated with the IPv6 QoS manager to study the effects of increasing traffic flows rates on the increased cost of delivering high priority traffic flows. The pricing agent assigns prices dynamically for each traffic flow accepted by the domain manager. Combining the pricing strategy with the QoS manager allows only higher priority traffic packets that are willing to pay more to be processed during congestion. This approach is flexible and scalable as end-to-end pricing is decoupled from packet forwarding and resource reservation decisions. Simulations show that additional revenue is generated as prices change dynamically according to the network congestion status.
TopIntroduction
Quality of service (QoS) is defined as the ability of a network element (e.g. an application, host, router) to have some degree of assurance that its traffic and service requirements can be defined (Shaikh, McClellan, Singh, and Chakravarthy, 2002). In other words, QoS is the ability of a network provider to support a user application’s requirements with regard to service categories through QoS parameters such as bandwidth, delay, jitter and traffic loss. These parameters are used to measure traffic flows at the end point to ensure that the users’ requirements are meet. QoS goals can be achieved by measuring and improving characteristics such as transmission rate and error rate. In order to achieve good QoS results, it is necessary to differentiate between traffic flows according to their data contents. It is also necessary to find if there are enough network resources to handle QoS requests issued by non tolerant traffic flows. Therefore, each component in an IP network must be equipped with new logical QoS supporting facilities and functionalities including admission control, reservation policies, packet classification and traffic shaping (Stader, 2001). Providing some form of end-to-end service differentiation in the Internet has been an important research issue and creates various on-going challenges to support end-to-end QoS in the Internet.
Integrated Services and Differentiated Service mechanisms provide QoS to real-time applications (e.g., IP voice, video, IPTV) by treating different types of traffic flows differently. IntServ introduces end-to-end per flow reservation, such that each flow is guaranteed a certain bandwidth along its path from the source to the destination. However, this approach requires maintenance of individual flow states in the routers, and its signaling complexity grows with the number of users. The differentiated service (DiffServ) architecture (Blake, Black, Carlson, Davies, Wang, & Weiss, 1998) was proposed as a more scalable solution to the end-to-end QoS problem, compared to previous approaches such as integrated services (IntServ) architecture (White, 1997). Intra-domain reservation is easily handled by sending QoS requests to a bandwidth broker that allocates preferred services to users as requested. The BB handles domain reservations, and flows exceeding their committed rates are dropped. The DiffServ scheme is scalable, however the mapping of traffic flows to predefined service classes is time consuming and limit the flexibility in the types of service offered. Also, inter-domain QoS reservations present problems, for if a destination host is located in a different QoS domain, the user application requires QoS guaranteed delivery through all the domains the traffic flow traverses.